Quantum dots, also known as nanometer crystals, belong to one kind of nanometer particles formed of II-VI group or III-V group elements. Particle diameters of quantum dots are generally from 1 nm to 20 nm. Since electrons and holes are qunatumly localized, and continuous energy band structure becomes a structure having discrete energy levels, quantum dots emit fluorescent light after being excited.
Emission spectrum of quantum dots can be controlled by changing sizes of quantum dots. By changing the sizes and elementary composition of quantum dots, it is possible to make their emission spectrum to cover the entire visible light region. Taking CdTe quantum dots as an example, when their particle diameters increase from 2.5 nm to 4.0 nm, their emission wavelength may be red-shifted from 510 nm to 660 nm.
At present, by means of luminescence characteristics of quantum dots, it is possible to apply quantum dots as molecule probes to fluorescence labeling, or to display devices. For example, while using monocolor quantum dots as a light emitting source of a backlight module of a liquid crystal display panel, monocolor quantum dots emit monochromatic light after being exited by blue light LEDs for example, and the exited monochromatic light is mixed with the blue light to form white background light. This kind of backlight source has a large color gamut and can improve picture quality.
Due to the poor dispensity of nanometer order quantum dots in organic solvent, quantum dot aggregation occurs, when they are used to manufacture patterns, results in the phenomenon of quenching, which severely reduces quantum yield. Therefore, there has been no design presently in which quantum dots are applied to liquid crystal display panels.